Ah I forgot hellaphone! I miss having a 9P interface to my texts that I could just mount and use with some rc scripts on my terminals. Sucks that I have an iPhone now where this is probably impossible or insanely hard to do.
If you want to make a 9P interface to SMS without running Hellaphone, you should start by looking into the RIL daemon. If I remember correctly, it runs at the Linux level (not Java) and drops a socket somewhere. The Java libraries for making phone calls, texts, etc. work by sending commands to that socket. You can read/write that socket yourself and use it to e.g. send SMS
